I have mine at max level for an "Oh Crap! Time to trade punches with the boss 1 on 1." Other than that, not a fan.
He did however drag the rest of my crew through to the Underworld where his effectiveness dropped significantly.

An interesting aspect of the Titan Shield ability: each of your Eddies in the party gets a shield. So if your Visions' shield breaks, you can tag in another Eddie and that Eddie's shield will be undamaged. Same goes for Mummy Eddie's Titan Shield (Bone Shroud). If you're not concerned about grinding XP, I'd seriously consider putting a Visions Eddie or Mummy Eddie in your party just for the Titan Shield.